Firefighters work at the site of an explosion near government buildings in Norway's capital. According to the BBC, the Norwegian police believe the bomb was the work of a terrorist group, although there was no word on which one.

Photograph Roald Berit/AFP/Getty Images.

A massive car bomb caused the explosion, a U.S. government source on the ground told ABC News.

Photograph by Jan Johannessen/AFP/Getty Images.

A building’s entrance is covered in debris.

Photograph by Aleksander andersen/AFP/Getty Images.

Injured people lie on the ground at the site of an explosion in Norway's capital, Oslo, on July 22, 2011. A Norwegian government minister told the BBC that an unknown number of people were still trapped in the buildings near where the bomb went off.

Photograph by Holm Morten/AFP/Getty Images.

Police evacuate a wounded woman after the explosion.

Photograph by Thomas Winje/AFP/Getty Images.

Medics treat injured people at the scene of the explosion near the government buildings in Norway's capital. Local news outlets reported that police believed that there may have been two other bombs around Oslo that did not explode.

Photograph by Roald, Berit/AFP/Getty Images.

People look at a damaged government building after a powerful explosion.

Photograph by Marianne Lovland/AFP/Getty Images.

People make phone calls near a burning government building. The exact details surrounding the explosion are still unclear, but police quickly confirmed that the blast was the result of a bomb.